1. Field of the Invention
The present invention relates to a drill chuck for use with electric or pneumatic drivers and specifically relates to a chuck possessing a sleeve member which can be operated manually or is self-locking and increases the gripping force.
2. Description of the Prior Art
A drill chuck of the prior art, as shown is FIG. 1, is chiefly comprised of body for receipt of a spindle, said body whose exterior having an adjustable cover shell and locking cover shell and said body having a plurality of jaw members disposed within the body member, where rotation of the adjustable cover shell controls the extension and retraction of the jaw members which grip or release the drill bit.
The user of a drill chuck of the prior art must rotate the adjustable cover shell with one hand while holding the drill bit inside the jaw members until the drill bit is locked in place. Not only is this awkward to handle, the limited surface available on adjustable cover shell often makes it difficult to determine whether or not enough gripping force has been applied between the drill bit and jaw members. If the gripping force around the drill bit is insufficient, the machine must be shut down and adjustable cover shell rotated by hand to tighten the drill bit. Besides being inconvenient, the adjustable cover shell and locking cover shell may still be in motion poising a risk of injury to the user.